Influência da temperatura de recozimento na conformabilidade da chapa trimetálica - 304L/A1/430 obtida por laminação a frio

Abstract

The industrial expansion has propelled the search for more efficient production processes and superior-quality materials capable of combining diverse properties. In this scenario, multilayer materials stand out, enabling the fusion of distinct characteristics. Cold rolling technique emerges as an economically viable approach for producing these materials, requiring significant plastic deformation to ensure bonding between layers. Consequently, an annealing process is necessary to eliminate the rigidity resulting from cold deformation and to enhance layer-to-layer adhesion through diffusion. However, thermal treatment of multilayer materials is intricate due to the formation of intermetallic compounds at layer interfaces. In this context, this study aims to investigate the mechanical properties and interfaces of a sheet composed of three distinct materials: stainless steel AISI 304L, aluminum AA1050, and stainless steel AISI 430. This sheet underwent thermal treatments of 3 hours at temperatures of 250, 350, 450, and 550 °C, in addition to untreated samples. Interface regions were analyzed using Energy Dispersive Spectroscopy (EDS) in conjunction with Scanning Electron Microscopy (SEM) images. Furthermore, the influence of thermal treatment on microstructure was evaluated through metallography. Formability was assessed through the forming limit curve obtained via Nakajima test, while adhesion between layers was evaluated through peel testing. Other mechanical properties were determined through tensile testing. Metallographic results indicated that aluminum was the most affected by temperature increase. Analysis via SEM and EDS revealed that the formation of a diffusion layer with micrometric thickness did not occur. However, the increase in thermal treatment temperature led to improved adhesion between layers, recrystallization of the Al1050 layer (with alteration in anisotropy), and reinforcement of mechanical properties, except for tensile and yield strengths. Between 350 and 450 °C, mechanical properties stabilized, with treatment at 350 °C providing an ideal balance between mechanical properties, adhesion, and performance in the limit curve of conformation. This demonstrates energetic advantages in industrial production of multilayer sheets. [resumo fornecido pelo autor]